Mine coaxial cable conducts alternating current instead of direct current

Mine coaxial cable is divided into four layers from inside to outside: central copper wire, plastic insulator, mesh conductive layer and wire sheath. The central copper wire and the mesh-like conductive layer form a current loop. It is named because the central copper wire and the mesh conductive layer are in a coaxial relationship.

Mine coaxial cables conduct alternating current rather than direct current, which means that the direction of the current is reversed several times per second.

If a normal wire is used to transmit high-frequency currents, the wire acts as an antenna that emits radio outwards, an effect that dissipates the power of the signal and reduces the strength of the received signal.

This cable is designed to solve this problem. The radio emitted by the center wire is isolated by the mesh conductive layer, which can control the emitted radio by grounding.

There is also a problem with this cable, that is, if a certain section of the cable is squeezed or twisted, the distance between the central wire and the mesh conductive layer is not consistent, which will cause internal radio waves to be reflected. back to the source of the signal.

This effect reduces the acceptable signal power. To overcome this problem, a plastic insulator is added between the center wire and the mesh conductive layer to ensure a consistent distance between them. This also causes the cable to be relatively stiff and not easy to bend.

The advantage of this cable is that it can support high-bandwidth communication over relatively long repeater-less lines, but the disadvantages are also obvious:

First, the volume is large, and the diameter of the thin cable is 3/8 inches thick, which takes up a lot of space in the cable duct;

The second is that it cannot withstand tangles, pressure and severe bending, which will damage the cable structure and prevent the transmission of signals; the latter is the high cost, and all these shortcomings are what the twisted pair can overcome, so in the current local area network environment , which has basically been replaced by the Ethernet physical layer specification based on twisted pair.